JP2016074031A - Electrode for projection welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to prevent electric conduction from one electrode to the other electrode even if an electrode advances when a component is not held on the electrode.SOLUTION: In an electrode for projection welding, a holding cylinder 33 is made of an insulation material and is provided with a through-hole 35 which communicates with an accommodation recess 34, and an electrode body 27 made of a conductive material is inserted in a through-hole 35 in the state such that the electrode body is capable of advancing and retracting. A regulation space 40 is formed between a stop surface 38 formed on the through-hole 35 and a reception surface 31 formed on the electrode body 27, and a space dimension L1 of the regulation space 40 is so set as to be smaller than a component storage depth L2 between an ends face 45 of the electrode body 27 and an end face 46 of the holding cylinder 33. Thus, when another party electrode 102 is advanced in the state of absence of a component, a non-conduction space 48 is formed between a plate 47 to which a component 1 is welded or the other party electrode 102 and the end face 45 of the electrode body 27.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an electrode for projection welding in which a part having a welding projection is supported by a holding cylinder combined with an electrode and welded to a plate material such as a steel plate or a stainless steel plate by electric resistance welding.

  Japanese Patent No. 3885213 discloses that a conductive material electrode is combined with an insulating material holding cylinder, the part is held in the holding cylinder, the electrode is advanced, and the part is welded to the steel plate part by electric resistance welding. ing.

Japanese Patent No. 3885213

  The technique described in the above-mentioned patent document has a problem that when the part is not held by the holding cylinder for some reason, the electrode directly hits the steel plate part and a welding current is applied.

  The present invention is provided in order to solve the above-described problems, and even when an electrode advances when a component is not held by the electrode, current is not supplied from one electrode to the other electrode. An object of the present invention is to provide an electrode for projection welding.

  According to the first aspect of the present invention, the holding cylinder in which the housing concave portion of the part is formed is made of an insulating material, a through hole communicating with the housing concave portion is formed in the holding cylinder, and the through hole is made of a conductive material. The electrode body is inserted in a state in which the electrode body can be advanced and retracted, and a restriction space is formed between the contact surface formed in the through hole and the receiving surface formed in the electrode body, and the space dimension of the restriction space is determined by the end face of the electrode body and the holding cylinder. By setting the depth smaller than the part accommodation depth between the end faces of the parts, the part is welded when the counterpart electrode advances toward the holding cylinder and the restriction space disappears in a state where the part is not present in the accommodation recess. An electrode for projection welding, characterized in that a non-conducting space is formed between a plate material or a counterpart electrode and an end face of an electrode body.

  When the component is held in the housing recess in a normal state, the plate material and the component are sandwiched between both electrodes, a welding current is applied, and the welding protrusion is welded to the plate material. At this time, since the advance displacement of the electrode is not transmitted to the holding cylinder, the space dimension of the restriction space remains unchanged.

  For some reason, such as forgetting to supply the worker or failure of the supply mechanism, the parts may not be supplied into the housing recess. When the counterpart electrode advances into such a place, the counterpart electrode presses the end surface of the holding cylinder, and the advance displacement is transmitted to the holding cylinder. Thereby, the contact surface formed in the through-hole adheres closely to the receiving surface formed in the electrode body. That is, the restriction space disappears. Even if such close contact is made, the space dimension of the restriction space is set to be smaller than the component housing depth between the end face of the electrode body and the end face of the holding cylinder, so that the space between the counterpart electrode and the end face of the electrode body In addition, a non-conductive space is formed. Therefore, when there is no part, continuity is always not established, and abnormal energization is prevented. If a welding current is applied in a state where the counterpart electrode is pressed against the end face of the electrode body, both electrodes are directly welded, and the welding equipment is damaged.

  When the parts are absent and the plate is not inserted, the non-conductive space is formed between the counterpart electrode and the end face of the electrode body, with the counterpart electrode closely contacting the end face of the holding cylinder as described above. The Further, when the component is absent and the plate member is inserted between the two electrodes, the non-conductive space is formed between the plate member and the end surface of the electrode body.

  Since the part is received in the housing recess of the holding cylinder, the part is held at the correct position with respect to the electrode, which is effective in improving the welding accuracy.

  A second aspect of the present invention is the projection welding electrode according to the first aspect, wherein a magnet is attached to the holding cylinder, and the magnetic lines of force of the magnet are arranged in the diameter direction of the receiving recess.

  When the component is small and light, such as a washer or a projection nut, if there is a slight inclination with respect to the housing recess, it may not enter the housing recess in a correct posture. Alternatively, such a problem also occurs when the electrodes are arranged in an inclined posture. As described above, since the magnet is arranged so that the lines of magnetic force are in the diameter direction of the housing recess, the component is attracted into the housing recess and guided into the housing recess in a correct posture. In particular, since the magnets are arranged so that the lines of magnetic force are in the diameter direction of the housing recess, the attractive force that draws the component into the housing recess acts uniformly on the entire component. For this reason, a force component that causes the component to tilt with respect to the housing recess is not generated, and the component enters the housing recess with a correct posture, so that reliability as an electrode is improved.

  If the polarity of the magnet is selected so that the line of magnetic force is in the same direction as the center axis of the electrode, the magnetic force acting on the entire part will have strong and weak parts, which will incline the part. There is a problem that it does not enter into the housing recess in a correct posture. Such a problem is solved as described above.

It is a top view of the whole component supply apparatus. It is (2)-(2) sectional drawing and perspective view of FIG. It is (3)-(3) sectional drawing of FIG. It is sectional drawing which shows the operation state of an electrode. It is the perspective view and sectional drawing of a projection nut. It is sectional drawing which shows another electrode structure. It is sectional drawing and a top view which show an electrode with a magnet.

  Next, a mode for carrying out the projection welding electrode of the present invention will be described.

  1 to 5 show a first embodiment of the present invention.

  First, a description will be given of the target parts for projection welding.

  There are various types of target parts, such as those in which a welding projection is formed on the head of the bolt with head, and those in which a welding projection is formed on the end surface of the cylindrical member. Here, it is the projection nut generally adopted. In the following description, the projection nut may be simply expressed as a nut.

  FIG. 5 shows the shape of the iron projection nut 1. A screw hole 3 is formed at the center of the square main body 2, and welding protrusions 4 are provided at four corners of the main body 2. In order to prevent the paint and water from entering the screw hole 3, an end cover 5 made of synthetic resin is fitted.

  Next, the component supply device will be described.

  The entire component supply device is denoted by reference numeral 100 and functions to supply the nut 1 to the electrode 101. A receiving recess 7 for the nut 1 is formed in an advancing / retracting supply member 6 formed of an elongated stainless steel square. The receiving recess 7 has an inlet opening 8 on the side surface side and an outlet opening 9 on the lower side.

  In order to prevent the nut 1 entering the receiving recess 7 from falling, a permanent magnet 10 that moves forward and backward is disposed above the supply member 6. The permanent magnet 10 is accommodated in a stainless steel square container 11, which is a nonmagnetic material, and is advanced and retracted by an air cylinder 12 fixed to the supply member 6. The piston rod 13 of the air cylinder 12 is advanced and retracted in the same direction as the advancing and retracting direction of the supply member 6, and the container 11 is fixed to the piston rod 13 by welding or the like.

  An air cylinder 16 is fixed to a base member 15 made of a thick stainless steel plate, and its piston rod 17 is coupled to the end of the supply member 6. An air cylinder 16 is arranged so that the piston rod 17 advances and retreats in the horizontal direction. The supply member 6 slides on the base member 15 by the forward / backward output of the air cylinder 16. An air cylinder 18 for raising and lowering the base member 15 in the vertical direction is fixed to a stationary member 19 such as a machine frame, and the upper end of the piston rod 20 is coupled to the lower surface of the base member 15.

  The nut 1 passes through the supply pipe 21 having a rectangular cross section, and its outlet end 22 matches the inlet opening 8. The supply pipe 21 is fixed to the stationary member 19 and extends from the parts feeder 23. An air injection pipe 24 for conveying the nut 1 at high speed is joined to the parts feeder 23.

  A sensor 25 that detects the presence or absence of the nut 1 is attached to a location ahead of the housing recess 7 when viewed in the advancing direction of the supply member 6. Here, a sensor 25 is attached to the tip of the supply member 6. As this sensor 25, various types of sensors can be adopted, but a magnetic substance detection type proximity switch which is generally used is suitable. The detection signal of the absence / presence of the nut 1 detected by the sensor 25 is transmitted to a control device (not shown), and the counterpart electrode 102 is advanced or prohibited from being advanced by an output signal from the control device. To do.

  Next, the electrodes will be described.

  Usually, an electrode for electric resistance welding is a pair of a stationary electrode on the stationary side and a movable electrode that moves forward and backward. In this embodiment, the electrode on the fixed electrode side is an electrode according to the present invention indicated by reference numeral 101, and the movable electrode corresponding thereto is the counterpart electrode 102. Although not shown, the counterpart electrode 102 is advanced and retracted in the vertical direction by advancing and retracting drive means such as an air cylinder and an advancing / retracting output type electric motor.

  An electrode body 27 made of a conductive material such as a copper alloy is coupled to a support member 28 that is a stationary member, and stands upright in the vertical direction. The electrode body 27 is a rod-like member having a circular cross section, and a large diameter portion 29 and a small diameter portion 30 are formed. A flat receiving surface 31 is formed at the boundary between the small-diameter portion 30 and the large-diameter portion 29, and this receiving surface 31 is on a virtual plane through which the central axis OO of the electrode body 27 passes in a vertical positional relationship. It is arranged. A flange 32 having a larger diameter than that of the large-diameter portion 29 is provided, and serves to receive a coil spring described later.

  The holding cylinder 33 is formed using a synthetic resin material having excellent heat resistance such as polytetrafluoroethylene or polyamide, or an insulating material such as a ceramic material. The holding cylinder 33 is formed with a circular accommodating recess 34 for receiving the main body of the projection nut 1, and a through hole 35 is provided in communication with the accommodating recess 34. The through hole 35 is constituted by a large diameter hole 36 and a small diameter hole 37, and a contact surface 38 is formed at a boundary portion between the large diameter hole 36 and the small diameter hole 37. The contact surface 38 is disposed on a virtual plane through which the central axis OO of the electrode body 27 penetrates in a vertical positional relationship. A restriction space 40 is provided between the contact surface 38 and the receiving surface 31, and the space dimension is indicated by L <b> 1.

  The large diameter portion 29 of the electrode body 27 is fitted in the large diameter hole 36 of the holding cylinder 33 in a slidable state. The small-diameter hole 37 is fitted in the small-diameter hole 37 so that the small-diameter portion 30 can slide. A long hole 41 in the direction of the central axis OO is opened in the holding cylinder 33, and a positioning pin 42 fixed to the electrode body 27 passes through the long hole 41. A coil spring 43 is inserted between the holding cylinder 33 and the flange 32, and the lower portion of the long hole 41 is pressed against the positioning pin 42 by the tension. In addition, since the lower side of the coil spring 43 is received by the insulating ring 44, the coil spring 43 is not energized.

  As described above, when the lower portion of the long hole 41 is pressed against the positioning pin 42, the space dimension L1 of the restriction space 40 is determined.

  The bottom surface of the housing recess 34 is formed by the end surface 45 of the electrode body 27, that is, the end surface 45 of the small diameter portion 30. The end face 46 of the holding cylinder 33 is disposed on a virtual plane through which the central axis OO of the electrode body 27 passes through in a vertical positional relationship. The distance between the end surface 45 of the electrode body 27 and the end surface 46 of the holding cylinder 33 is the component housing depth L2.

  By setting the space dimension L1 of the restriction space 40 to be smaller than the component housing depth L2 between the end surface 45 of the electrode body 27 and the end surface 46 of the holding cylinder 33, the nut 1 is not present in the housing recess 34. When the counterpart electrode 102 advances toward the holding cylinder 33 and the restriction space 40 disappears, the non-conducting space 48 (see FIG. 5) is formed between the plate material 47 or the counterpart electrode 102 to which the bolt 1 is welded and the end face 45 of the electrode body 27. 4 (B)) is formed. This spatial distance is indicated by the symbol L3.

  If the counterpart electrode 102 advances when the nut 1 is missing in the housing recess 34 due to the operator's forgetting to supply the nut or failure of the nut supply device, the counterpart electrode 102 is directly attached to the holding cylinder 33. The holding cylinder 33 descends while abutting against the end face 46 and contracting the coil spring 43, the contact face 38 comes into close contact with the receiving surface 31, and the relative position between the holding cylinder 33 and the electrode body 27 remains unchanged. In this unchanged state, a non-conductive space 48 is formed.

  Next, a normal operation state will be described.

  In this embodiment, the nut 1 is in a back-out state with the welding protrusion 4 facing upward. When the nut 1 is sent vigorously from the parts feeder 23, it enters the receiving recess 7 with that momentum. At that time, as shown in FIGS. 1 and 2, the permanent magnet 10 stands by at the center of the receiving recess 7, so that the nut 1 is attracted by the permanent magnet 10, and the welding projection 4 is formed in the receiving recess 7. It is sucked into the ceiling and stopped at that location.

  Next, the supply member 6 advances by the operation of the air cylinder 16, and the sensor 25 detects that the nut 1 is not present in the accommodation recess 34 during the advancement. This detection signal of the absence of nut is sent to a control device (not shown). When the sensor 25 passes over the accommodation recess 34 and the nut 1 comes directly above the accommodation recess 34 and the screw hole 3 of the nut 1 is coaxial with the central axis OO, the supply member 6 advances at that location. Stops. After the stop, the outlet opening 9 of the receiving recess 7 approaches the housing recess 34 by the lowering operation of the air cylinder 18.

  Thereafter, when the permanent magnet 10 is moved to a position removed from the housing recess 34 by the operation of the air cylinder 12, the nut 1 falls by its own weight and fits in the housing recess 34. This stuck state is indicated by a two-dot chain line in FIG. When the nut insertion into the housing recess 34 is completed, the supply member 6 returns to the original position by the operation of the air cylinder 18 and the air cylinder 16. The sensor 25 detects that the nut 1 is correctly inserted into the housing recess 34 during the return. This nut presence detection signal is sent to the control device.

  Thereafter, a plate material 47 such as a steel plate component is placed on the upper side of the nut 1. Then, when the counterpart electrode 102 advances, the plate material 47 and the nut 1 are sandwiched between the counterpart electrode 102 and the end face 45 of the electrode main body 27, and subsequently, a welding current is energized, and FIG. As shown, the welding projection 4 is welded to the plate material 47. This weld is indicated by reference numeral 39. When the presence of the nut 1 is detected by the sensor 25 while the supply member 6 is returning, the detection signal becomes a trigger signal and the counterpart electrode 102 is advanced.

  In the normal state shown in FIG. 4A, since there is a gap between the lower surface of the plate material 47 and the end surface 46 of the holding cylinder 33, the holding cylinder 33 is not pushed down. The spatial dimension L1 is not reduced.

  Next, an abnormal operation state will be described.

  When a failure occurs in the operation of the component supply device 100 or the sensor 25 and the nut 1 is not supplied to the receiving recess 34, the counterpart electrode 102 advances to a place where the plate material 47 and the nut 1 are not present. There is. In this case, the mating electrode 102 pushes down the end surface 46 of the holding cylinder 33 while the coil spring 43 is compressed, so that the contact surface 38 comes into close contact with the receiving surface 31 and, as shown in FIG. The dimension L1 disappears. Since the space dimension L1 is set to be smaller than the component housing depth L2, when the space dimension L1 becomes zero, a non-conduction space 48 (L3) is formed in the housing recess 34. The non-conduction space L3 is (L2-L1).

  As a result of the non-conductive space 48 (L3) being provided in this way, the electrical conductivity between the counterpart electrode 102 and the electrode body 27 is interrupted, and even if a welding current is applied, no current is applied between the electrodes. The occurrence of abnormal welding between the electrodes is prevented.

  4B shows the state in which the counterpart electrode 102 has advanced to the place where the plate material 47 is inserted and the holding cylinder 33 is pushed down via the plate material 47, the plate material 47 is inserted. Even if not, the non-conductive space 48 (L3) is left as described above.

  It should be noted that an electric motor that performs forward / backward output can be employed instead of the various air cylinders. In addition, illustration of a supply pipe for working air is omitted from each air cylinder. Similarly, illustration of signal wires connected to the sensor is also omitted. Furthermore, it is possible to replace the various permanent magnets with electromagnets.

  The above-described advance / retreat operation of the supply member, permanent magnet, counterpart electrode, etc., and the operation such as air injection can be easily performed by a generally adopted control method. By combining an air switching valve that operates with a signal from a control device or a sequence circuit configured by a simple computer device, a sensor that emits a signal at a predetermined position of the air cylinder and transmits it to the control device, etc. Operation can be ensured.

  The operational effects of the first embodiment described above are as follows.

  When the nut 1 is held in the receiving recess 34 in a normal state, the plate material 47 and the nut 1 are sandwiched between the electrodes 102 and 27, the welding current is applied, and the welding projection 4 is formed in the plate material 47. To weld. At this time, since the electrode 102 displacement is not transmitted to the holding cylinder 33, the space dimension L1 of the restriction space 40 remains unchanged.

  The nut 1 may not be supplied into the housing recess 34 due to some reason such as forgetting to supply the worker or failure of the component supply device 100. When the counterpart electrode 102 advances to such a place, the counterpart electrode 102 presses the end face 46 of the holding cylinder 33, and the advance displacement is transmitted to the holding cylinder 33. Thereby, the contact surface 38 formed in the through hole 35 is in close contact with the receiving surface 31 formed in the electrode body 27. That is, the space of the restriction space 40 disappears. Even if such close contact is made, the space dimension L1 of the restriction space 40 is set to be smaller than the component housing depth L2 between the end surface 45 of the electrode body 27 and the end surface 46 of the holding cylinder 33. A non-conducting space 48 (L3) is formed between 102 and the end face 45 of the electrode body 27. Therefore, when the nut 1 is not present, continuity is always not established, and abnormal energization is prevented. If the welding current is applied with the counterpart electrode 102 pressed against the end face 45 of the electrode body 27, the electrodes 102 and 27 are directly welded, and the welding equipment is damaged.

  When the nut 1 is absent and the plate material 47 is not inserted, the non-conductive space 48 is in close contact with the end face 46 of the holding cylinder 33 as described above, and the counter electrode 102 and the electrode body 27 are in close contact with each other. Formed between the end face 45 of each of the two. When the nut 1 is absent and the plate material 47 is inserted between the electrodes 102 and 27, the non-conductive space 48 is formed between the plate material 47 and the end face 45 of the electrode body 27.

  Since the nut 1 is received in the housing recess 34 of the holding cylinder 33, the nut 1 is held at the correct position with respect to the electrode body 27, which is effective for improving the welding accuracy.

  FIG. 6 shows a second embodiment of the present invention.

  In the second embodiment, unlike the first embodiment, the small diameter portion 30 and the large diameter portion 29 are not formed in the electrode body 27, the large diameter portion 29 is replaced with the flange 49, and the upper surface of the flange 49 is the receiving surface. 31. Other configurations are the same as those of the first embodiment including the portions not shown, and members having the same functions are denoted by the same reference numerals.

  The operational effects of the second embodiment are the same as those of the first embodiment.

  FIG. 7 shows a third embodiment of the present invention.

  In the third embodiment, a magnet 52 is attached to the holding cylinder 33. The magnet 52 is a permanent magnet, and the two magnets 52 are arranged facing each other in the diameter direction of the housing recess 34. That is, the two magnets 52 are arranged on a straight line. A hole is formed in the holding cylinder 33, and a magnet 52 is inserted therein and sealed with a lid member 53. When viewed in the diameter direction of the housing recess 34, the N pole and S pole of the magnet 52 are also opposed to each other in the same direction, so that the lines of magnetic force 54 are arranged in the diameter direction of the housing recess 34. Other configurations are the same as those of the previous embodiments, including the portions not shown, and members having the same functions are denoted by the same reference numerals.

  When the component is small and light, such as a washer or a projection nut, if there is a slight inclination with respect to the housing recess 34, the housing recess 34 may not enter the correct posture. Alternatively, such a problem also occurs when the electrode 101 is arranged in an inclined posture. As described above, since the magnet 52 is arranged, the nut 1 is attracted into the housing recess 34 and guided into the housing recess 34 in a correct posture.

  In particular, since the magnets are arranged so that the lines of magnetic force 54 are in the diameter direction of the housing recess 34, the attractive force that pulls the nut 1 into the housing recess 34 acts uniformly on the entire nut 1. For this reason, the force component which the nut 1 inclines with respect to the accommodation recessed part 34 does not generate | occur | produce, but the nut 1 enters the accommodation recessed part 34 with a correct attitude | position, and the reliability as the electrode 101 improves.

  If the polarity of the magnet 52 is selected so that the magnetic force line 54 is in the same direction as the central axis OO, a strong magnetic field and a weak magnetic field are generated in the magnetic force acting on the entire nut 1. There is a problem that the nut 1 is inclined and does not enter the receiving recess 34 in a correct posture. Such a problem is solved as described above. Other functions and effects are the same as those of the previous embodiments.

  As shown in FIG. 7A, the N pole and S pole of the permanent magnet 10 are set so as to face each other in the same direction as the diameter direction of the housing recess 34, and the magnetic lines 55 of the permanent magnet 10 and the magnetic lines 54 of the magnet 52 are made the same. Set the direction. By doing so, both lines of magnetic force act on the nut 1 without interfering with each other, so that the suction to the receiving recess 7 and the suction to the receiving recess 34 are performed independently of each other, such as malfunction due to the interference. Occurrence can be prevented.

  As described above, according to the electrode of the present invention, even if the electrode is advanced when the component is not held by the electrode, current is not supplied from one electrode to the other electrode. Therefore, it can be used in a wide range of industrial fields such as automobile body welding processes and home appliance sheet metal welding processes.

DESCRIPTION OF SYMBOLS 1 Projection nut, components 2 Main body 3 Screw hole 4 Welding protrusion 6 Supply member 7 Receiving recessed part 27 Electrode main body 31 Receiving surface 33 Holding cylinder 34 Housing recessed part 35 Through hole 38 Contact surface 40 Restriction space 45 End surface 46 End surface 47 Plate material 48 Non-conduction Space 52 Magnet 54 Line of magnetic force 100 Component supply device 101 Electrode 102 Counter electrode L1 Restriction space L2 Component accommodation depth L3 Spatial distance OO of non-conduction space Center axis

Claims (2)

  The holding cylinder in which the concave part of the component is formed is made of an insulating material, and a through hole is formed in the holding cylinder so as to communicate with the concave part of the holding part. A restriction space is formed between the contact surface formed in the through hole and the receiving surface formed in the electrode body, and the space dimension of the restriction space is determined by the component housing depth between the end surface of the electrode body and the end surface of the holding cylinder. If the counter electrode is advanced to the holding cylinder and the restriction space disappears in a state where the component is not present in the housing recess, the plate material to which the component is welded or the end surface of the counter electrode and the electrode body is set. An electrode for projection welding, wherein a non-conducting space is formed between the electrodes.   The projection welding electrode according to claim 1, wherein a magnet is attached to the holding cylinder, and the magnetic field lines of the magnet are arranged so as to be in a diameter direction of the housing recess.

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